Engine power management to reduce power during shifting is known for on-road trucks, in efforts to improve transmission longevity. Compared to on-road trucks, agricultural and other off-road vehicles operate at substantially slower travel speeds and can operate in some conditions offering less traction, which can lessen at least some types of loading and other forces in off-road transmissions. Transmissions in such off-road applications therefore can experience different operating parameters and different considerations for ensuring acceptable use lives compared to on-road trucks. However, agricultural and other off-road vehicles such as self-propelled applicators including sprayers and spreaders are getting larger.
As self-propelled applicators get larger, the power requirements to operate the spray systems, dry product delivery system, and other accessories have correspondingly increased. Engines with higher torque output ratings have been used to meet the increased power requirements of recent self-propelled applicators. When comparing on-road trucks to self-propelled applicators, an on-road truck can have relatively more of its engine power output utilized for propelling the truck and its load whereas a self-propelled applicator can have a substantial amount of its engine power output utilized for powering its operational systems including various auxiliary systems such as sprayer or spreader systems and large hydraulic systems to hydraulically power boom folding and other movements as well as to hydraulically power front wheel assist drive systems.
Transmission ratings are greatly influenced by the abilities of clutches that perform drive ratio changes or the shifts. The transmission is typically capable of more torque transfer when the drive ratio is static versus when the drive ratio is changing or shifting gears. Accordingly, the transmission has both a relatively greater non-shifting-state transmission ratings) and a relatively lesser shifting-state transmission rating(s) that correspond to a relatively greater non-shifting-state clutch rating(s) and a relatively lesser shifting-state clutch rating(s).
However, some of the high output engines required to power the various systems of larger self-propelled applicators can deliver more torque during operation than the shifting-state clutch ratings of the transmissions. Heavy duty industrial off-road transmissions with shifting-state clutch ratings that match or exceed power output ratings of such high output engines are expensive, large, and heavy. Known attempts to implement such high output engines in the larger self-propelled applicators typically include using control systems that always limits engine torque across its entire power band so that engine torque output never exceeds the shifting-state clutch ratings) of the transmission.